Question
I have a china doll plant and just the past few days the leaves have started to change from a nice green to a green and brownish color. Do you know what could be causing this. Thanks

Answer
Matt,

I suspect that you are overwatering it and it may be getting a fungal infection that China Dolls seem to be getting easily when overeatered. I suggest you cut back on the water. This fungal infection is called Corynespora leaf spot. The only description of this problem I could find follows: Symptoms of Corynespora leaf spot vary depending upon the host. Lesions start on lower leaves, especially those in contact with the potting medium or those which
are wounded. Lesions expand rapidly and are black and may encompass the entire leaflet and cause abscission when conditions are favorable. There is rarely any halo surrounding lesions on China Doll.
Control - Keep plants as free of excess water as possible and avoid crowding to promote rapid drying of foliage. Mixed results in controlling this disease have been seen with the fungicides available.

This means you should be very careful to keep water off the stems and
any foliage and empty the drain tray 1/2 hour after watering. I suggest that you repot the plant into a pot that is 30 cm in diameter and replace as much soil as possible without disturbing the roots too much. After that make sure you water the plant lightly and let the top half of the soil in the pot get dry before watering again. You can get a bamboo skewer to insert in the soil and don't water it until it comes out with the top half dry. I would also try spraying the plant twice a week with Lysol spray  making sure that you get the fronts and backs of all leaves and the surface of the soil. It contains a fungicide that I have found frequently works well on plants without causing problems in that home or office as long as it is used regularly until the problem has disappeared and been gone for at least a month. Then you should be able to safely stop without the problem coming back. Good luck!

Darlene